Integrated circuits or microchips (or chips) are generally manufactured on a single wafer of semiconductor material (e.g., silicon). These individual microchips are later cut out of the wafer. Each integrated circuit on each microchip has contact pads that are electrically coupled to the electrical circuits and subcircuits embedded therein. Contact pads are exposed in wafer or microchip form before the microchips are packaged and are, thus, accessible with properly designed probes. A selected number of microchips are tested by automated test equipment that utilize probe rings and probe cards which have a number of probes that access the microchips to ensure they meet design specifications.
As shown in FIGS. 1A, 1B, and 1C, a conventional probe ring assembly 50 generally consists of conventional probe ring 11 that has central opening 11 which provides access to microchip 20 to be tested, together with a series of spaced conductive individual flexible metallic needles or blades (probes) 12 arranged on conventional probe ring 10 around central opening 11. Each probe 12 extends from a location away from conventional probe ring 10 toward the center of central opening 11, traversing both the outer perimeter 15 of conventional probe ring 10 and inner perimeter 16 of central opening 11 of conventional probe ring 10. As discussed above, probes 12 are adapted to electrically contact selected contact pads on microchip 20, which are electrically coupled to the rest of the integrated circuitry embedded in microchip 20, so that electrical signals may be transmitted to and from the integrated circuit on microchip 20. These signals transmit test routines that test the functionality of specific integrated circuits embedded in microchip 20. Epoxy layer 17 holds probes 12 in position and, if necessary, electrically insulates probes 12 from each other and from conventional probe ring 10, which may consist of anodized Aluminum.
As shown in FIGS. 2A, 2B, and 2C, conventional probe ring assemblies 50 are usually designed to fit a conventional printed circuit board opening 14 in a conventional printed circuit board 20 to form a conventional probe card 30. One end of probes 12 are then soldered to selected contacts 70 on conventional printed circuit board 20 to selectively electrically couple contacts 70 to probes 12 to relay signals to and from contact pads, of microchip 20 to test selected integrated circuits embedded on microchip 20. Note contacts 70 are generally oriented in a "star-burst" pattern around conventional printed circuit board opening 14 of conventional printed circuit board 20. Conventional printed circuit board 20 aligns with central opening 11 of conventional probe ring assembly 50 when conventional probe ring assembly 50 and conventional printed circuit board 20 are fitted together. Plated-thru holes 75 are used to make electrical connections through conventional printed circuit board 20. First end 31 of conventional probe card 30 is, in turn, inserted into various types of testing equipment that are used to generate and transmit the test routines that test the functionality of the integrated circuits and subcircuits of microchip 20. Electrical components, such as capacitor 40, may be placed on conventional probe card 20 in the electrical path 33, between contacts 70 and the contact leads 32 on first end 31 of conventional printed circuit board 20, such as a printed circuit trace, which generally consists of plated copper. In addition, electrical components may be placed between bands 71 and 72 that are generally used as common ground and/or power sources. Bands 71 and 72 are, in turn, generally connected to an appropriate electrical path 33 used as a ground or power source by the testing equipment with which conventional probe card 30 interacts. These electrical components adjust or modify the electrical signals transmitted to and from the integrated circuit via conventional probe ring assembly 50 and conventional probe card 30 for a variety of reasons. For instance, capacitors 40 are generally used to increase the accuracy of the test results by reducing the overall distortion.
Conventional probe ring assemblies 50 and conventional probe cards 30 have a number of problems. For example, the placement of electrical components, such as capacitor 40, on conventional printed circuit board 20 itself slows and interrupts the transmission and reception of electrical test signals to and from the selected integrated circuits being tested. The distance between the selected integrated circuit being tested on microchip 20 and the capacitor 40 in conventional embodiments is, unfortunately, rather large in microscopic terms, which slows down the overall speed of the circuit and increases the distortion (e.g., due to the time delay associated with the capacitors and transient or ripple condition created by the capacitors). Most semiconductor manufacturers appreciate the significance of both of these factors and that conventional probe ring assemblies 50 and conventional probe cards 30 do not alleviate these concerns.